Thermally isolated variable diameter deployable shield for spacecraft

Abstract

A thermally isolated deployable shield for spacecraft is provided utilizing a plurality of lattice panels stowable generally against the craft and deployable to some fixed distance from the craft. The lattice panels are formed from replaceable shield panels affixed to lattice structures. The lattice panels generally encircle the craft providing 360 degree coverage therearound. Actuation devices are provided for translating the shield radially outward from the craft and thermally isolating the shield from the craft. The lattice panels are relatively flexible, allowing the shield to deploy to variable diameters while retaining uniform curvature thereof. Restraining devices are provided for holding the shield relatively tight in its stowed configuration. Close-out assemblies provide light sealing and protection of the annular spaces between the deployed shield and the crafts end structure.

What is claimed is: 
     
       1. A thermally isolated variable diameter deployable shield for spacecraft, said shield being stowable generally adjacent said craft and deployable to a fixed distance from said craft, said shield comprising: a plurality of relatively flexible lattice structures capable of flexing to varying curvatures;   a plurality of replaceable shield panels each being removably attached to one of said lattice structures so as to form a lattice panel therewith;   securing means for removably securing said shield panels to said lattice structure, and for allowing said shield panels to flex in conjunction with said lattice structure;   actuation means for securing said lattice panels relative said craft and for controllably positioning said lattice panels a fixed distance from said craft; and   restraining means for holding said shield relatively tight against said craft prior to deployment of said shield.   
     
     
       2. The shield as defined in claim 1 wherein said lattice structure comprises a lattice web to which is affixed relatively rigid upper and lower longitudinal members and relatively flexible ring members. 
     
     
       3. The shield as defined in claim 1 wherein said lattice panels generally encircle said craft providing 360 degree radial coverage thereof. 
     
     
       4. The shield as defined in claim 3 wherein said lattice panels comprise four 90 degree panels providing 360 degree radial coverage. 
     
     
       5. The shield as defined in claim 2 wherein said lattice panels are thermally isolated from said craft's framework. 
     
     
       6. The shield as defined in claim 5 wherein said thermal interfaces comprise bearing elements having minimum roller/race interface. 
     
     
       7. The shield as defined in claim 2 wherein said actuation means comprises a plurality of spring actuators attached to said craft's structural framework and said lattice structure by thermally isolating bearing elements, said actuators defining the diameter of said deployed shield. 
     
     
       8. The shield as defined in claim 7 wherein said spring actuators comprise: a spring loaded pivot arm further comprising a pivot end attachable to said craft and a shield end slidably attachable to said lattice structure with said thermally isolating bearing elements;   a spring assembly; and   a telescoping arm residing generally within said spring assembly locating said spring assembly relative said pivot arm and said craft, said telescoping arm pivotably secured to said craft and said pivot arm with said thermally isolating bearing elements.   
     
     
       9. The shield as defined in claim 8 wherein said shield end is slidably attached to said lattice structure by means of a bearing element sliding within a slotted trunnion bracket. 
     
     
       10. The shield as defined in claim 9 wherein said spring actuators comprise a plurality of medial actuators disposed longitudinally relative said craft and said lattice panel along said lower longitudinal member centerline of each of said lattice structures, and a plurality of side actuators disposed generally equally along sides of said lattice panels along said lower longitudinal members and oriented perpendicular to said medial actuators. 
     
     
       11. The shield as defined in claim 10 comprising four medial, spring actuators and eight side actuators. 
     
     
       12. The shield as defined in claim 8 wherein said spring assembly comprises a helical compression spring. 
     
     
       13. The shield as defined in claim 8 wherein said spring assembly comprises a concentric double spring assembly. 
     
     
       14. The shield as defined in claim 1 further comprising folding hinge assemblies disposed between and affixed to said lattice panels, said hinge assemblies foldable when said shield is stowed and expandable upon deployment of said shield so as to form make-up shielding material between said lattice panels providing continuous 360 degree radial coverage around said craft. 
     
     
       15. The shield as defined in claim 1 wherein said securing means comprises quick-acting floating fasteners which provide a relatively bind-free interface between said shield panels and said lattice structure. 
     
     
       16. The shield as defined in claim 1 wherein said restraining means comprises at least one tension band which generally encircles and holds said shield against said craft's structural framework, and a pyrotechnically actuated trunnioned tension bolt assembly holding said tension band together, so that actuation of said bolt assembly releases said tension band to allow said shield to deploy. 
     
     
       17. The shield as defined in claim 1 further comprising a plurality of flexure close-out assemblies providing light sealing and protection of annular areas between said deployed shield and an end structure of said craft. 
     
     
       18. The shield as defined in claim 17 wherein said flexure close-out assemblies further comprise a plurality of flexure elements having cut-out reliefs permitting said flexure elements to flex with the varying curvatures of said lattice structure, and means for attaching said flexure elements to the end of said lattice structure and the end close out and light seal assembly of said craft, said attaching means acting between said flexure element cut-out reliefs. 
     
     
       19. The shield as defined in claim 18 wherein said means for attachment of said flexure element comprises a bushing arrangement further comprising a thrust surface and a spring mechanism so that said flexure elements are held against said thrust surface by said spring mechanism. 
     
     
       20. Apparatus for deploying panels of a craft's variable diameter deployable shield from a stowed configuration generally against a craft to a larger diameter deployed configuration at some distance from said craft, said apparatus thermally isolating said panels from said craft, comprising: a plurality of medial spring actuators oriented longitudinally relative said craft and said panel, said medial actuators slidably attached to the centerline of said panel and nonslidably attached to framework of said craft so that said medial actuators translate said panel outward a fixed distance from said craft upon panel deployment; and   a plurality of side actuators oriented perpendicular to said medial spring actuators and located generally equally spaced along sides of said panel, said side actuators slidably secured to edges of said panel and nonslidably secured to said craft framework so that upon deployment said side actuators locate the sides of said panel radially outward matching said fixed distance of said panel when deployed.   
     
     
       21. The apparatus defined in claim 20 whereby said thermal interfaces comprise bearing elements having minimum roller/race interface areas. 
     
     
       22. The apparatus defined in claim 21 wherein said actuators comprise: a spring loaded pivot arm further comprising a pivot end attachable to said craft and a shield end slidably attachable to said panel with thermally isolating bearing elements;   a spring assembly; and   a telescoping arm residing generally within said spring assembly locating said spring assembly relative said pivot arm and said craft, said telescoping arm pivotably secured to said craft and said pivot arm with said thermally isolating bearing elements.   
     
     
       23. The apparatus as defined in claim 22 wherein said shield end is slidably attached to said panel by means of a thermally isolating bearing element sliding within a slotted trunnion bracket affixed to said panel. 
     
     
       24. The apparatus as defined in claim 22 wherein said spring assembly comprises a helical compression spring. 
     
     
       25. The apparatus as defined in claim 22 wherein said spring assembly comprises a concentric double spring assembly. 
     
     
       26. A thermally isolated deployable shield for spacecraft having variable diameter capability, said shield being alternately positionable between a stowed configuration generally adjacent said craft and a deployed configuration a fixed distance therefrom, comprising: four relatively flexible lattice structures of length generally equal to that of said craft, said lattice structures capable of flexing to varying curvatures, comprising a lattice web to which is affixed relatively flexible ring members and relatively rigid upper and lower longitudinal members, said lower longitudinal members along the sides and centerline of said lattice structure;   replaceable shield panels removably attached to said lattice structures with quick-acting floating fasteners allowing said shield panels to flex in conjunction with said lattice structures, said lattice structures and attached shield panels comprising four 90 degree lattice panels generally encircling said craft;   foldable hinge assemblies disposed between and affixed to said lattice panels, said hinge assemblies being foldable when said shield is in said stowed configuration thereof and expandable when said shield is in said deployed configuration thereof so as to comprise make-up shielding material between said lattice panels providing continuous 360 degree radial coverage;   thermally isolating actuation means for securing said lattice panels relative said craft and for driving said lattice panels from their stowed configuration to their deployed configuration, said actuation means comprising four medial spring actuators per said lattice panel disposed longitudinally relative said craft and slidably secured to said lattice structure's centerline lower longitudinal member and nonslidably secured to said craft's framework so that upon deployment said medial actuators translate said lattice panel outward a fixed distance dictated by said actuator, and eight side actuators oriented perpendicular said medial actuators and disposed generally equally along said lattice panel sides, said side actuators being slidably secured to said side lower longitudinal members of said lattice structure and nonslidably secured to said craft's framework so that upon deployment said side actuators locate said lattice panel edges radially outward matching the deployed distance of said medial actuators, said side and medial actuators slidably and nonslidably secured with thermally isolating bearing elements;   restraining means for securing said shield relatively tight against said craft prior to deployment thereof, comprising a plurality of tension bands generally encircling and holding said shield against said craft's structural framework, and a pyrotechnically actuated tension bolt assembly holding said tension band together whereby upon actuation thereof said tension band releases allowing said shield to deploy;   four flexure close-out assemblies per said lattice panel ends providing complete 360 degree annular space light sealing and protection, said assemblies comprising a plurality of flexure elements having cut-out reliefs permitting said flexure elements to flex with the varying curvatures of said lattice structure, and bushing arrangements acting between said flexure element cut-out reliefs for attaching said flexure elements to said lattice structure and said craft's close out and light seal assembly, said bushing arrangements comprising a thrust surface and a spring mechanism so that said flexure elements are held against said thrust surface by said spring mechanism.